Singer and songwriter Lou Reed, a leader of the ground-breaking rock group the Velvet Underground, has died at age 71. He's seen here in the 1970s.

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Lou Reed, the singer and songwriter whose work as a solo artist and as the leader of cult-favorite band The Velvet Underground influenced generations of musicians, has died at age 71.

Rumors of Reed's possible demise have been circulating for the past week; his death was first reported Sunday by Rolling Stone. The magazine notes that he received a liver transplant earlier this year.

Update at 3:45 p.m. ET: Reed's literary agent, Andrew Wylie, has confirmed to NPR that Reed died Sunday morning at 11, of complications related to his liver transplant. We've made slight changes to this post to reflect that confirmation. Our original post continues:

Lewis Allan "Lou" Reed was born in Brooklyn, N.Y., in 1942. The musician's official Facebook page didn't announce his passing overtly, choosing instead to post a photo titled "The Door" Sunday morning. More than 1,000 notes of condolence and grief soon followed.

Reed's songs as a guitarist for The Velvet Underground and later during his solo career blended art and noise in deceptively simple combinations, with his New York-inflected voice telling stories of street deals and odd characters.

"One chord is fine," he said of his approach to the guitar, in Rolling Stone's obituary. "Two chords are pushing it. Three chords and you're into jazz."

In a remembrance of Reed, NPR's Neda Ulaby quotes his Velvet Underground co-founder and longtime collaborator John Cale explaining that the band didn't care to make things easy for their listeners:

"We were not user-friendly at all," Cale told NPR in 2000. "Anyone listening to a bass guitar and regular guitar coming out of the same amp — it couldn't have been a really great listening experience."

Along with Cale on viola, bass and other instruments, the band's core personnel included drummer Moe Tucker and guitarist Sterling Morrison. Bassist Doug Yule later replaced Cale in the lineup.

The band's first two albums, The Velvet Underground & Nico (1967) and White Light/White Heat (1968), became touchstones of art-rock for generations that followed. A third self-titled album, produced without Cale, included the mournful "Pale Blue Eyes."

In a career that spanned New York's Andy Warhol-era experimental art scene and included the unlikely hit "Walk on the Wild Side," Reed never lost his sense of urban grit and cool.

"Walk on the Wild Side came from Transformer, Reed's second solo album that was produced by David Bowie and released in 1972. On the strength of that single and songwriting gems such as "Perfect Day" and "Satellite of Love," the album cemented Reed's status as a star whose music will be played for decades to come.

As Neda reports, "Walk on the Wild Side" was Reed's only Top 40 hit; the song's iconic bass line has been sampled and evoked by musicians producing everything from rock and club music to hip-hop.

Reed is survived by his wife, the musician Laurie Anderson; the pair wed in 2008.